In FIG. 1, there is schematically illustrated part of a known printer device (e.g., a large format printing device) having an array of printheads 100 in a parallel row. More specifically, FIG. 1 illustrates six printheads 102-112. Each of the printheads 102-112 includes a plurality of printer nozzles (not shown) for firing ink 114, 116 onto a print medium 120. Although FIG. 1 depicts the printer device as having six printheads 102-112, printer devices have been known to possess any number of printheads, e.g., two, four, or more.
The printheads 102-112 are typically constrained to move in a direction 170 with respect to the print medium 120, e.g., paper. In addition, the print medium 120 is also constrained to move in a further direction 160. During a normal print operation, the printheads 102-112 are moved into a first position with respect to the print medium 120 and a plurality of ink droplets 114, 116 are fired from the same plurality of printer nozzles contained within each of the printheads 102-112. After completion of a print operation, the printheads 102-112 are moved in a direction 170 toward a second position and another print operation is performed. In a like manner, the printheads 102-112 are repeatedly moved in a direction 170 across the print medium 120 and a print operation is performed after each such movement of the printheads 102-112. When the printheads 102-112 reach an edge of the print medium 120, the print medium is typically moved a short distance in a direction 160, parallel to a main length of the print medium 120, and another print operation is performed. The printheads 102-112 are then moved in a direction 170 back across the print medium 120 and yet another print operation is performed. In this manner, a complete printed page may be produced.
A more detailed description of the printer device illustrated in FIG. 1 may found in commonly assigned application Ser. No. 09/502,667 filed on Feb. 11, 2000, by Xavier Bruch et al., the disclosure of which is hereby incorporated by reference in its entirety.
In order to maintain the quality of the printed output of the printer device, it is generally known to maintain the nozzles in substantially proper operating condition. In this respect, a service station 140 is typically provided along a travel path of the printheads 102-112. The service station 140 is typically configured to maintain the health of the printheads 102-112 by performing servicing operations on the printheads, e.g., a means for wiping, collecting spit ink, capping the nozzles, etc. The service station 140 typically includes a plurality of service station units 142-152 for performing servicing operations on the each of the printheads 102-112. Generally speaking, a respective service station unit 142-152 is provided for each of the printheads 102-112. The service station units 142-152 are typically housed within a service station frame 154.
A servicing protocol is typically implemented to control the times and manner in which the printheads 102-112 are serviced. For example, in one respect, if it is detected that certain of the nozzles of the printheads 102-112 have not fired any ink drops for a certain period of time, the printheads are moved to a position over the service station 140 and caused to fire a normally set number of ink drops to thereby clean out the nozzles. In addition, a wiping mechanism positioned in the service station 140 may be caused to wipe excess ink off the nozzles to thereby increase the probability of their proper functionality. In another respect, the protocol may cause the printheads 102-112 to spit a set number of ink drops into the service station after each printing pass in an effort to substantially prevent ink from drying within the nozzles. The servicing protocol typically sets the number of times as well as the frequency of servicing operations based upon a set of normal values which are themselves typically set by the printhead or service station manufacturer. In addition, the normal values of the servicing protocol may vary according to the set printmodes.
The above-described servicing process is generally known as an open loop servicing technique. That is, the servicing protocol that determines when to service the printheads 102-112 as well as the degree of servicing to be applied, takes into consideration certain variables, e.g., time uncapped, drops fired during last printing pass, time in cap, etc. However, these types of servicing protocols typically apply a relatively heavy treatment to greater ensure proper printhead performance regardless of the age of the printheads 102-112. One problem associated with the open loop servicing technique is that ink may be wasted by virtue of spitting more ink drops than is necessary, oftentimes resulting in faster aging of the printheads as well as the service station.
Printer devices have also been known to include a drop detector module 130 operable to detect whether the nozzles of the printheads 102-112 are properly firing ink. In these types of printer devices, servicing operations on the printheads 102-112 may be triggered by detected errors, e.g., clogged nozzles, and a user's expectations, e.g., desired print quality. It is generally known to position the printheads 102-112 over the service station 140 and spit a certain number of ink drops to clean out the ink in the nozzles. This servicing process is generally known as a closed loop servicing technique. That is, servicing on the printheads 102-112 may occur based upon a closed loop servicing protocol under normal operating conditions, with extra, possibly lighter, servicing operations being performed based upon detected errors, e.g., clogged nozzles. In this regard, the closed loop servicing technique has certain advantages over the open loop servicing technique (e.g., does not waste a relatively large amount of ink, extends the life of the printheads and service station, etc.). However, printer devices that implement the closed loop servicing technique are relatively more expensive and complicated and thus may be unsuitable for certain types of printers (e.g., less expensive printer models).
The age of the service station 140 typically has an impact on the effectiveness of the servicing operation as well as its efficiency. That is, relatively new (or younger) service stations generally perform servicing operations relatively more effectively and efficiently than relatively older service stations. In this respect, older service stations are typically less capable of performing servicing operations in a substantially adequate manner than newer service stations, within the confines of an open loop servicing algorithm. The performance of service stations typically tend to deteriorate with time by virtue of a plurality of factors, e.g., aerosol, ink, wear, dust, etc. Known open loop servicing techniques are generally ill-equipped to compensate for the aging of the service stations. One result of failing to compensate for the aging of the service stations is that when the same level of servicing is performed by an aged service station, the level of servicing may be insufficient to maintain the printheads in relatively proper operating condition, or may otherwise result in wasted ink and unnecessary stress applied on the printheads.